Field of the Invention
The present invention relates to an aqueous low friction coating for telecommunication cables. In particular, the present coating includes one or more fluoropolymer latexes, a non-fluoropolymer latex, and a polyaziridine that can be applied onto polymer substrate.
Background
Proliferation of Fiber to the home (FTTH), fiber to the premise (FTTP) or, more generally, fiber to the X (FTTx) networks requires the installation of new optical cable links in existing premises or buildings. Frequently, these new fiber optic cables need to be fished through walls, run through existing cable ducts or through other confined spaces. Preferred optical fiber cables used in this last link in the FTTx network are generally small and flexible and can be difficult to push through already crowded existing cable ducts or other confined spaces as a result of friction between the cable sheath of the optical fiber cable being installed with existing cables as well as with the cable duct itself. Thus, having an optical fiber cable having a low friction surface is highly desirable in order to facilitate the installation of new cables into existing building structures.
For example, inorganic particulates (e.g. talc), silicone materials or fatty acid amides have been incorporated into the material outer cable jacket in some telecommunication and electrical cables in the extruder in order to reduce the coefficient of friction of the resulting cable. Extrusion of a low friction jacket material in this manner requires that the lubricative material be dispersed throughout the bulk phase of the cable jacket rather than being disposed at the outer surface of the telecommunication cable where it is needed to provide beneficial low friction characteristics. If these materials are not adequately tied into the jacket resin matrix, low molecular weight components can bleed out of the cable jacket matrix, reducing the low friction performance of these materials over time.
Fluoroplastics have excellent mechanical and electrical properties including low friction coefficients and good self-lubricating performance. Currently, fluoroplastics are widely used in chemical industry, electronics, electrical engineering, aviation, aerospace, textiles, construction, automobiles and other industrial fields. However, the intrinsic characteristics of fluoroplastics can make processing very difficult. While dispersing of fluoroplastics including Polytetrafluoroethylene (PTFE) in polymer binders for lubricating coating applications is known, these coatings generally lack the desired level of durability due to the non-compatibility between PTFE and the non-fluoroplastic polymers or poor adhesion of the coating to polymer substrates such as the materials commonly used as telecommunication cable jacket materials.
Thus, what is needed is a robust and durable low friction coating that can stand up to repeated abrasion without decreasing the low friction behavior of the coating.